There’s a certain clumsiness about the Facebook ad that congressional investigators say Kremlin-connected Russian internet trolls targeted at Marylanders in 2015. Along with pictures of Freddie Gray, Michael Brown and Tamir Rice, it included the slightly off-key text, “Join us because we care. Black Matters!” — as if it were the color that was important and not the lives of black people. The ad sent those who clicked on it to a Facebook page called Black Matters U.S. — again, not quite getting the phrase right — that appears associated with a website that included pointed but stilted commentary about matters including race and policing. Those who would seek to downplay the evidence that Russia sought to influence the presidential election in Donald Trump’s favor could point to the fact that the ad appeared aimed at riling up Hillary Clinton’s base in a state the Democrat carried easily.

But that misses the point. As The Sun’s John Fritze reported, the ad represented not the Russians’ best efforts to stir the pot in the United States but a starting point in a years-long effort to sow division and ultimately influence the election. The fact, as Sen. Richard Burr of North Carolina points out, that more of the targeted ads were aimed at electorally insignificant states like Maryland, Missouri and Georgia than the crucial ones of Wisconsin and Michigan isn’t a sign that we should stop worrying. Rather, if we consider the evolution of the Russian effort, we can only conclude that they are learning fast. What may initially have been a ham-handed social media push got much more sophisticated by the time the election rolled around, and we can only expect it to get more so by the midterms in 2018 and the next presidential contest in 2020.

Examples of ads released by the congressional intelligence committees show that by the fall of 2016, the Russians were pushing much more effective buttons — getting out voters for Trump rallies in the crucial state of Florida; galvanizing Christian conservatives by comparing Ms. Clinton to Satan and acknowledging that even though “Donald Trump isn’t a saint by any means, he’s at least an honest man and he cares deeply for this country”; blaming the shooting of a policeman on Black Lives Matter (yes, it got the term right that time); fomenting anti-Muslim sentiment by claiming “invaders” were coming to the United States to implement Sharia law; driving Bernie Sanders supporters away from Ms. Clinton by highlighting his criticism of the Clinton Foundation; and seeking to turn veterans and military supporters against Ms. Clinton by referring to the Benghazi attacks.

The attempts to sow discord haven’t stopped. In September, Sen. James Lankford, an Oklahoma Republican, cited evidence that Russian Twitter trolls were stoking both sides of the controversy over kneeling NFL players.

Representatives of Facebook, Twitter and Google were raked over the coals in a series of congressional hearings this fall. All three admitted that they should have done better at policing foreign sponsored political content in the lead-up to the election, and Twitter, for example, has banned ad buys from some known Russian propaganda operations. But it appears unlikely that they will voluntarily match the level of transparency traditional media outlets do when it comes to revealing who is paying for political advertisements, much less engage in a serious effort to weed out false information spread on their platforms.

Congress could step in, but although the grilling of the tech firms was a bi-partisan affair, any legislative fix will be hampered by President Trump’s insistence that the entire story of Russian interference in the election is fake news. As recently as two weeks ago, Mr. Trump gave credence to Russian President Vladimir Putin’s denials of any attempt to meddle in 2016 and said continued efforts to bring it up were hindering U.S.-Russian relations. He and his defenders can’t get over the notion that admitting Russian interference diminishes the legitimacy of his election. That’s a false premise. We haven’t seen any evidence to suggest that the Russian efforts were the decisive factor in 2016. But based on the rapid evolution of their methods, they might be in 2018 and beyond if we don’t take the threat seriously now.